Regulating system



Aug. 6, 1940. R. A. BRADEN REGULATING SYSTEM Filed- May 28, 193s Patented ug. 6, 1940 UNITED STATES PATENT OFFICE REGULATING SYSTEM Rene A.Braden, Collingswood, N. J., asslgnor to Radio Corporation of America, a corporation Yof Delaware 4-Claims.

This invention relates to regulatingsystems such as are utilized' to regulate the voltage or current of an electrical load circuit, and has for principal object the provision of an improved regulating system and methodl of operation Whereby the regulated characteristic is rendered independent of variation in the cathode heating of the electron discharge device which is controlled by the current flowing through the load circuit.

In the form of regulating circuit in which the voltage at the plate of an electron discharge device is controlled by the current owing through the load.y and the plate voltage of the control device is amplified and applied to thegrld of a regulating device which is so connected that the flowing to the '.foad passes through its cathode-anode current, diculty is frequently encountered due to the fact that variations in the cathode-heating current of the control device tend '55o produce similar variations in the current flowing throughthe regulating device and the load.

It has been proposed to avoid this diiculty by the provision of means for regulating the cath ode heating current oi the control device but such means are necessarily aoniewhat expensive and involve various complications of the system.

In accordance with the present invention, the effect of variation in the control device cathode heating current on the load current is avoided by an improved system wherein the load current is utilized to heat the cathode of the control device from which the control grid potential of the regulating device is derived. Under these conditions, any load current change resulting from variation in the control device cathode heating current operates through the cathode heating circuit of the control device to neutralize the elect of such variation. As hereinafter shown, the control device may be either an amplifier which also has its control grid potential varied in accordance with the load current or a diode which controls the grid potential of an amplifier interposed between it and the control grid circuit of the regulating device.

The invention will be better understood from the following description considered in connec tion with the accompanying drawing and its scope .is indicated by the appended claims.

Referring to the drawing,

Figure l is a Wiring diagram of a regulating system wherein grid control potential is applied to the regulating device through an amplier comprising one or more electron tubes in cascade and having the cathode heating current and the control grid potential of the first tube (the control device) both responsive to the load circuit current, and- Figure 2 illustrates a similar system wherein grid control potential is applied to the regulating device through a control amplifying channel which has its input potential controlled by a dlode having a cathode heating circuit connected in series with the load.

The system of Fig. l includes supply terminals it and I l from which current is supplied through the cathode-anode circuit of a regulating device i2, the cathode heating circuit i3 of a control amplifier it and a resistor l5 to a load circuit lli.

'The control amplifier it has its screen grid potential applied through a resistor il and a glow tube lil, the purpose of which is to keep screen voltage constant, derives its cathode anode potential from the terminals l0 and il through a resistor l@ and derives its control grid potential from the resistor l5 through a bias battery 2t. It should be noted that the control grid of the regulating device l2 is connected to the junction between the resistor i9 and the anode oi the control amplifier ld and that an adjustable resistor 2i is provided for by-passing any desired part of the load circuit current, around the i-llament or cathode heater i3 of the control tube ld.

Under these conditions, the control grid potential of the regulating device l2 is dependent on the potential drop of the resistor it) and this potential drop is determined by the cathodeancde current of the control amplifier irl. The cathode-anode current of the amplifier lil is of course determined by two factors both ci which are dependent on the current of the circuit i6. Thus increase in the load current causes a more positive or less .negative control grid voltage to be applied to the amplifier lil and at the same time increases the electron emission at the cathode of this amplifier. The result is that the cathode-anode current of the amplifier it is increased, the potential drop of the resistor lil is likewise increased, the control grid potential of the device i2 is made more negative and the current of the load device is restored to a value equal to its original value plus a small increment which ei-I ects the regulating action; the greater the voltage amplir'lcation between the grid of the control tube and the grid. of the regulating tube, the smaller the increment will be. Even with a "singie amplifying tube, as shown in Fig. l, the increment' is only a small fraction of the change that would occur without a regulator if either the load resistance or the applied voltage changed.

Sil

The function of the rheostat 2l is to hiv-pass all of the load current except that required for proper 'excitation of the illament of M. After the required load current is gotten by adjustment of the potentiometer I5, the current through the lament may be regulated to its normal value by reference to the ammeter 3d. This will cause a slight change in the load current, which can be corrected if desired by a slight readdustment of I5. Since a particular position on potentiometer I5 corresponds quite accurately to a certain current, it is possible to couple the adjustments of ZI andy I5 through a suitable mechanical linkage so that the proper lament current is maintained as the load current is varied betweenwide limits by adjustment of I5.

It is ordinarily desirable that tube I4 be one having a lament-type cathode of small heat capacity, so that it will respond rapidly to changes in load current. However, heater-type cathodes may bev used if a delay of several seconds in complete response to a change in the circuit is permissible.

The system of Fig. 2 is similar to that of Fig. l in' some respects but diiers therefrom in that the control amplifier I` is replaced byv a diode 22 which functions to control the input potential of a control channel which includes the ampliers 23 and 2d. The amplifier 23 derives its cathodeanode potential from 'the terminals I-ll through a resistor 25 and the lower section oi a resistor 26, a glow tube: 2l being provided for stabilizing the cathode potential of this amplifier. .The amplier 2d derives its cathode-anode potential from the terminals' iii-l l through the resistor I9 and the lower two sections of the resistor 26, an additional glow tube I8 being provided to stabilize-thevoltage at the cathode of the amplier 2tand at the screen grid/of the amplifier 2d. Screen grid potential is applied toA the amplifier 2d from a terminal'intermediate the tWo upper sections of the resistor 2%.

It will be noted that cathode-anode potential is applied to the diode 22 through a resistor 2s and that the diode filament is connected in series with the load circuit i6.

In the operation of the system of Fig.` 2, increase in the loadv current releases more electrons at cathode of the diode 22, greater current is transmitted through the resistor ,29, the control grid of the amplifier is made more negative, less current is transmitted through the resistor 25, the control grid of the ampliiler 2d is made more positive, more current is transmitted through the resistor I 9, the grid potential of the regulating device I2 is made more negative and the current of the load circuit it is restored to its normal value. How this e'ect is reversed when the load current decreases will be apparent without detailed explanation.

The circuit is caused to stabilize itself at the required load current by adjustment of the screen and platev voltages applied to tubes 23 and 26, adjustment of the magnitudes of resistance I@ and 25, and by regulation of the iilament shunt rheostat 2 I, the latter being adjustable only within limits which will not dam-age tube 22 or make it inoperative. However, this adjustment may be facilitated by a rliostat 33, which provides a means of adjustment of the voltage between grid and cathode of 28 which is independent oi' diode 22. This rheostat also adds to the regulating action. but. in practice, this part of its action will be relatively small compared with the effect of the diode.

I claim as my Invention:

l. The combination of current supply terminals, a regulating device provided with control grid and cathode-anode circuits, a control device provided with cathode heating and cathodeanode circuits, a load circuit connected to said device provided with cathode heating and 'cathode-anode circuits, a load circuit connected to said supply terminals through the cathode-anode circuit of said regulating device and through the cathode heating circuit of said control device, means responsive to variation in the current of said cathode heating circuit for controlling the control grid circuit potential of said regulating device, and means 'for diverting a part of the load circuit current from said cathode heating circuit.

3. The combination of current supply terminals, a regulating device provided with control grid and cathode-anode circuits, a control device provided with cathode heating and cath= ode-anode circuits, a load circuit connected to said supply terminals through the cathode-anode circuit of said regulating device and' .through'the cathode heating circuit of said control device, an amplier arranged to have its output voltage controlled both in response to variation in the current through said cathode heating circuit and in response to the total load current, means for applying to the control grid circuit of said regulating tube a potential dependent on the output of said ampliiier, and means for. simultaneously adjusting the proportion of the load circuit current transmitted through said cathode heating circuit and the magnitude of said total load current.

4. The combination or current supply terminals, a regulating device provided with control grid and cathode-anode circuits, a control device provided with control grid, cathode heating and cathode-anode circuits, a load circuit connected to said supply terminals through the cathode-anode circuit of said regulating device and through the cathode heating circuit of said control device, and separate meansV responsive respectively to variation in the current of said cathode heating circuit and to the total load current for controlling the control grid circuit potential of said regulating device,rand means for simultaneously adjusting said separate grid potential control means.

- RENE A. BRADEN. 

